Air heater



AIR HEATER Filed July 14, 1921 2 Sheets-Sheet 1- d am: 2

WWE illm 30 20 im? i@ f 42 IH gli gwoewtox April 15, 1924. 1,490,088

, L. B. BRIDGES AIR HEATER Filed July 14. 1921 2 Sheets-Sheet 2 '16 L9 34mg@ le@ Il e.:

Owl? 33g Patented Apr. 15, 1924.

UNITED STATES PATENT OFFICE.

LEWIS B. BRIDGES, OF BROOKLYN, NEW YORK, ASSIGNOR TO AIRDRY CORPORATION, OF GROTON, NEW YORK, A CORPORATION 0F NEW YORK.

AIR HEATER.

Application filed .'l'uly 14, 1921. Serial No. 484,725.

To all ycf/'wmf t muy concern.:

Be it known that l, Lewis B. Binnens, a citizen of the United States, and resident of the borough of Brooklyn, in the county of Kings, city and State of New York, have invented certain new and useful Improve-A ments in Air Heaters, of which the following is a specification. y

This invention relates to improvements in air heaters, and more particularly to means for heating air yby electricity. The improved electric heating means is especially adapted for use in connection with sanitary drying apparatus and appliances in which the drying is effected by means of a blast of heatedair, and is preferably mounted in the discharge nozzle of the fan blower or other air-supplying means. It will be obvious, however, that the .improved heating means is not limited .in its application to the types of devices and apparatus specified but may be employed in lines, conduits and casings of various kinds for heating air, etc.

The invention hasv for its principal objects to provide simple, inexpensive and durable electric heating means; to provide a heating element so constructed as to permit the use of a maximum length of resistance wire on a heating element of given size; to provide a heating element which will uniformly heat a blast of air passing through a nozzle or conduit; to provide a ,short heating element of small size adapted for use in conduits nozzles of small diameter in which a large an'iount of resistance wire is so wound upon a support as to uniformly and rapidly heat. the air and also so as not to interfere with the free flow of the air through the conduit; and to provide a heating element which may be readily assembled and dis. mantled.

To the above and other ends, which will hereimifter appear, the invention consists in the features of leonstruction, arrange ments of parts, and combinations of devices hereinafter more fully described and particularly pointed out in thc appended claims.

In the accompanying drawings, wherein the preferred embodiment of the invention is illustrated.

Figure 1 is a fragmentary vertical sec-V tional view of a fan blower of ordinary construction having the improved air heat- Fig. 2 a horizontal section on the line 2 2 of Fig. 1;

'Figs 3 and ll end elevations on an enlarged scale of the inner and outer ends, respectively, of the heating coil or element;

Fig. 5 a perspective view on an enlarged scale of the support or core upon which the resistance wire is wound;

Figs. 6 and 7 plan views of the vertical and horizontal members, respectively, of which the core is formed; f

rig. 8 an end elevation on `an enlarged scale of the outer end of the insulating and supporting ring carrying the line terminals;

Fig. 9 a perspective view of one of the line terminals or contacts on the ring;

Fig. l() a plan view of a blank from which the terminal or contact shown in Fig. 9 is formed; and

Fig. 11 a detail view showingl a slightly modilied form of resistor.

Referring to the various parts by numerals, 11 designates the fan or rotor chamber of a fan blower of ordinary construction and 19. the discharge nozzle of the blower. At the inner end of the nozzle 12 a ring 13 of insulating material is rigidly but vdetachably held by means of one or more screws 14. Ring 13 is provided atdiametrically opposite points with two thickened portions 15 having flat vertically disposed faces. A pair of stationary contacts or line terminals 16 are fastened to the flat inner vfaces of the portions 15 of ring 13, each contact having an intermediate horizontal portion doubled upon itself, and upwardly and downwardly extending portions or ears 1T, each formed integrally with one web or thickness of the doubled portion of the contact. Fastening screws 18 extend through said ears and are threaded only partly through the thickened portions of the ring 13, so that each contact is rigidly held to the ring and is insulated from the nozzle 12 The webs of the doubled portion 4W16 of each contact are provided with superposed and closely adjacent resilient tongues 19 which extend longitudinally of the 'nozzle beyond-the outer edge of ring 13, the outer ends of the tongues on each contact being bent or flared away from each other to facilitate the -en trance of one of the cooperating knife contacts, hereinafter described, therebetween. A pair of line wires 2O and 2l are connected with the contacts 16, each line wire being connected with its associated contact by one of the fastening screws 1S which also serves as a binding post.

The heating element or coil is removably mounted in the nozzle and comprises generally a tubular insulating and protect-ing casing 22 having a core or support detachably secured therein upon which is wound the resistor or length of resistance wire. Casing` 22 and ring 13 are formed of rigid insulating material, such as vulcanized fiber. The resistor core or support comprises two sheets of mica 23 and 24:, each of which is as wide at one end as the internal diameter of casing 22 and has its longitudinal edges tapered or inclined toward each other so that the opposite end thereof is comparatively narrow. In the construction shown, the narrow ends of sheets 23 and 2li are substantially half as wide as the wider ends thereof, but it will be obvious that the relative widths of the opposite ends of the sheets may be varied. The longitni'linal edges of sheets 23 and 2t are )referably straight for a short distance at the wide ends of `:aid sheets, as shown at 25 and Q6, respectively, in order to afford a substantial bearing of the edges of the sheets against the inner side of casing 22 at these points, as more fully hereinafter described.

Sheets 23 and Qt are slotted longitudinally centrally thereof from the narrow ends of said plates to a point midway' the ends of each plate, as more clearly shown in Figs. G and 7. The sheets are then interlocked with each other, as shown in Fig. 5, with the wider portion of sheet 23 engaged in slot 2T in sheet 24C and the wider part of sheet engaged in slot Q8 in sheet 23, said sheets being located in intersecting planes at right angles to each other so as to form a sleieton core having four radially extending blades or wings each of which is tapered longitudinally of the core. It will be observed that the core thus formed is cruciform in transverse section and is wide vertically and narrow horizontally at one end while at the other end said core is narrow vertically and wide horizontally. As the two sheets are of uniform size and shape, the core midway its ends is as wide horizontally as it is vertically and, owing to the reverse taper of the sheets, the shape of the core in transverse section varies from end to end of the core while the distance around the core remains the same.

A combined brace and locking bar 29 of metal is riveted to the narrow end of sheet 23 at opposite sides of slot Q8 by rivets 80, said bar engaging in a short slot 3l in sheet 24 and preventing endwise separation of the sheets as well as supporting the divided portions of the sheet Q3. The divided portions of sheet 24 are supported by combined braces and knife contacts 32 which form the terminals of the resistor coil. Each contact and brace 82 is of angular or L-shape, one contact having its short vertical arm secured to one side of sheet 23 by a rivet 33 above sheet 24 and having its horizontal arm secured to the upper side of one divided portion of sheet 24 by a rivet 34, while the other Contact 32 has its short vertical arm secured by a rivet 33 to the opposite side of sheet 23 below sheet 24 and its horizontal arm secured by a rivet 84C to the. under side of the other divided portion of sheet 24C. The contacts are thus completely insulated from each other by the mica sheets and also serve in connection with bar 29 to rigidly comiect the sheets, maintaining the same at right angles and against relative endwise or other movement, said contacts serving also to support the divided portions of sheet 9.4.

One end of the resistor coil, which ronsists of suitable resistance wire, is connected with the contact 3Q located above sheet 24 by means of a binding screw passing through sheet 23 and the vertical arm of said contact and having a binding nut 3G screwed thereon. 3T is wound spirally around the skeleton core from the inner to the outer end of the core where it is passed through a metal eyelet 88, thence along one side of sheet 23 below sheet 24 to the inner end of the core, where it is passed through a second eyelet 39 in sheet 23 and connected with the other Contact 32 by a second binding screw 35 and nut 36. It will be observed from the foregoing description of the wire that each convolution of the core will be of different shape but that the convolutions will be formed of uniform lengths of wire. This arrangement affords a maximum length of wire in a coil of given length and diameter, a highly eifective distribution of the wire in the path of the air, and avoids choking of the air passage through `the heating element and excessive concentration of heat at one point.

l The core with the resistor wound thereon is adapted to be inserted in and removed endwise from the protecting and insulating casing Q2. Then inserted in said casing said core has a four point support therein at each end, I'neventing lateral movement of the core, and is also held against rotary n1ovenient in the casing. The four points of support at the outer end of the core comprise straight edge portions 26 of sheet 24 and shoulders 40 on bar 29, all of which engage the inner surface of the cylindrical casing. Bar 29 is provided with projections 41 at its ends which engage in short longitudinal slots ft2 in the outer end of casinfr 90 see Fig.

The resistance wire 1, thus preventing relative rotary movement between the core and casing. If desired, a thin resilient sheet metal latch hook, such as hook 43, may be riveted to the exterior of casing l22, as at 44, said hook having its laterally bent end adapted to engage the outer edge of one end of bar 29. This hook serves to detachably lock the core in the casing so that the heating element may be freely handled in assemblingthe same in the nozzle and so that the parts thereof vwill not become separated in shipment or handling thereof. The four points of support at the inner end of the core comprise straight edge 'portions 25 of sheet 23 and the outer ends of the combined contacts and braces 32, all

- of which engage the inner surface of casing 22. v

The inner end of casing 22 is adapted to abut against ring 13 when the heater is inserted in nozzle 12 so as to arrestthe inward movement of the heater after knife contacts 32 thereon pass between spring tongues 19 on the line terminals 16 secured to ring 13. The heater is detachably held in theV nozzle by a resilient split ring 45 adapted to be sprung into and out of a shallow circumferential channel 46 in the nozzle and engaging against the outer end of casing 22 and also against the outer edge of bar 29. Said ring thus holds the casing in the nozzle and, by reason of its engagement with bar 29 assists hook 43 to hold the core in place. yIf hook 43 be omitted, core 23-24V will be held against endwise movement incasing 22 in either direction, when the heater is placed in the nozzle, by means of bar 29 and ring 45. The longitudinal edges of the mica sheets 23 and 24 areprovided with notches 47 in which the resistance wire 37 is engaged to maintain the convolutions of the wire in properly spaced relation. Rivets 30, 33 and 34, and rivets 48 and 49 serve to prevent separation of the laminations of the mica sheets 23 and 24. The engagement of contacts 32 between tongues 19 of contacts 16 assists bar 29 in preventing rotation of the core in the casing.

In Fig. 11 a slightly modified form of resistor is shown, the portions of the resistance wire 37 between the wings of the core being coiled in helical form, thus greatly increasing the length of wire in a heater of given diameter and length. f

Vhat I claim is:

1. An electric heater comprising a support, and a resistor wound spirally around said support in convolutions formed of the same length of wire, the convolutions at opposite ends of the resistor having an elongated form in end view, the degree of elon- 'gation of the convolutions progressively diminishing with each turn of the resistor from both ends of the resistor to a point intermediate the ends thereof.

2. An electric heating coil comprising a helically wound conductor having all its convolutions formed of the same len th of wire, the convolutions atopposite si es of a point substantially midway the ends of the coil having an elongated form in end View, the degree of elongation of the convolutions increasing with each turn of the coil from said point toward the ends of coil, and all of the convolutions at one side of said point having their lines of greatest diameter in a plane at a right angle to the plane of the lines of greatest diameter of the convolutions at the opposite side of said point.

3. A helical resistor ,having a series of convolutions differing in shape in end view and each formed of the same length of wire.

f4. An electric heater comprising an elongated skeleton core of insulating material varying in shape in transverse section between its ends, and a resistance wire wound spirally around said core, said core being so shaped that the convolutions of the wire are of substantially the same length.

5. An electric heater comprising an'elongated core cruciform in transverse section, the pairs of parallel wings of the core tapering towards opposite ends of the core, and a resistance wire ywound spirally around said core.` K

6. An electric heater comprising an elongated` core of insulating material having wings radiating from the longitudinal axis thereof, certain of said wings tapering toward one end of the core and the other wings tapering toward the opposite end of the core, and a resistor wound spirally around said core. f 7 An electric heater comprising an elongated core having four resistor supports arranged radially around the a-Xis of the core, and a resist-ance wire wound spirally around said core in contact with the outer edges of said supports, said supports having their outer edges located closer to the axis of the core at oneend of the core thanat the other end and the pairs of oppositely disposed supports being arranged in reverse relation.

8. An electric heater comprising a tubular casing of insulating material, a resistor core of insulatingl material detachably mounted in said casing, said core having four radial wings, two parallel wings of the core tapering toward one end of the core and the other `two wings taperingtoward the opposite end of the core, the side edges of the wider end of each wing engaging the inner surface of thecasing, and a resistor wound around said core and supported by the outer edges of said wings.

9. An electric heater comprising a tubular casing of insulating material, a resistor core of insulating material detachably mounted in said casing, said core having four radial wings, two parallel wings of the core tapering toward one end of the core and the other two wings tapering toward the opposite end of the core, the side edges of the wider end of each wing engaging the inner surface of the casing, a resistor wound around said core and supported by the outer edges of said wings, and means for detachably locking the core in the casing against endwise movement.

10. An electric. heater comprising a tubular casing ot insulating material, a resistor coreJ of insulating material detaohably mounted in said easing, said core having four radial wings, two parallel wings of the core tapering toward one end of the core and the othertwo wings tapering toward the opposite end ot the core, the side edges of the wider end of eac-l1 wing engaging the inner surface of the casing, a resistor wound around said core and supported by the outer edges of said wings, and means for removably holding the core in the` easing against endwise and rotary movements.

ll. An electric heater comprising a tubular casing ot insulating material, a resistor core of insulating` material detachably mounted in said casing, said core having four radial wings, two parallel wings of the core tapering toward one end of the core and the other two wings tapering toward the opposite end of the core, the side edges of the wider end of each wing engaging the inner surface ot the casing, a resistor wound around said core and supported by the outer edges of said wings, resistor terminals held to the narrow ends of one pair of oppositely disposed wings and'. extending outwardly into engagement with the casing to brace the core, and a brace bar held to the narrow ends of the. other pair of wings and engaging the inner surface ot the casing at its ends.

l2. An electric heater comprising a tubular casing of insulating material, a resistor core of insulating` material detachably mounted in said easing, said core having :tour radial wings, two parallel wings of the core tapering toward one end of the core and the other two wings tapering toward the opposite end of the core, the side edges ot the wider end of each wing engaging the inner surface of the casing, a resistor wound around said core and supported by the outer edges ot said wings, resistor terminals held to the na row ends ot one pair of oppositely disposed wings and extending outwardly into engagement with the casing to brace the core, and ay brace bar held to the narrow ends of the other pair of wings and engaging the inner surface of the casing at its ends, said bar having projections at its ends engaging in slots in the adjacent end ot the casing.

18. An electric heater comprising a tubular casing of insulating material, a resistor core of insulating material detachably mounted in said casing, said core having four radial wings, two parallel wings of the core tapering toward one end of the core and the other two wings tapering toward the opposite end of the core, the side edges of the wider end of each wing engaging the inner surface of the casing, a resistor' wound around said core and supported by the outer edges ot said wings, resistor terminals held to the narrow ends of one pair of oppositely disposed wings and extending outward into engagement with the casing to brace the core, a brace bar held to the narrow ends of the other pair of wings and engaging the inner surface of the casing at its ends, said bar having projections at its ends engaging in slots in the adjacent end of the casing, and a latch held to the casing for holding said bar in engagement with said slots.

14. The combination with an air discharge nozzle, of a ring of insulating material secured within said nozzle, line terminals held to said ring, a heating element removably held in said nozzle having a tubular casing fitting within the nozzle and abutting against said ring at its inner end, and means detachably held to the outer end of the nozzle for preventing outward movement of the casing, said heating element having resistor terminals frictionally engaging the line terminals.

` l5. A heating element comprising two sheets of insulating material slotted longitudinally from opposite ends and interlocked with each other to form a core having four radially disposed wings, said sheets being tapered toward opposite ends ot the core, bracing means connecting the ends of the slottedV portion Aof one sheet, angular resistor terminals, means rigidly securing the resistor terminals to opposite faces of the other sheet at opposite sides ot the slot therein, means rigidly securing the resistor terminals to the intersecting sheet at opposite faces of the intersecting sheet, and a resistor connected at its ends with said terminals and wound spirally around said core.

In testimony whereof I hereunto ailix my signature.

LEWIS B. BRIDGES, 

